In the field of microelectronics, an electrostatic discharge can occur throughout the lifetime of an integrated circuit, and can constitute a genuine problem for the reliability of this integrated circuit, as well as a major cause of malfunction.
An electrostatic discharge is generally manifested by a current peak of varying amplitude and varying duration.
An ESD protection device should therefore remove this current peak. Furthermore, this current peak induces a thermal stress in the protection device.
One conventional ESD protection element is a triac. The production of such a protective element in a technology of the bulk-substrate type readily makes it possible to dissipate the heat generated by the ESD pulse through the contacts and the bulk substrate in which the protective element is produced.
Furthermore, ESD protection devices of the triac type are generally associated with triggering circuits, for example, MOS transistors whose gate and substrate are connected to ground (GGNMOS transistors), connected to their gate. This presence of a triggering circuit makes it possible to reduce the triggering voltage of the protection device. The triggering voltage of such a device is the voltage applied between the two terminals of the device, beyond which the device starts to conduct. However, the presence of a triggering circuit has a negative effect on the surface size of the assembly.
In particular, when the protection device is produced in a given CMOS technology on a bulk substrate, moreover, the absence of a triggering circuit leads to high triggering voltages, which may be greater than the breakdown voltage of a transistor produced in the technology and capable of being protected by this protection device.